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Marty, Mercedes Technician

Category: Mercedes

Satisfied Customers: 50450

Experience: Bosch Certified Master Tech. Over 35 years experience.

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my ac..component a9 (AC compressor) has open circuit or short circuit

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hi, my AC dos not work so i have chacked in the Meracedea main computer and i have ricived the following :"BI1640: the component or the signal line to the component A9 (AC compressor) has open circuit or short circuit "can you rell me waht is mean and if the compresor needed to be change?

Hi, I'm sorry that you are still having trouble with the a/c system. I am going to be away until Tuesday. Can you post your VIN number for me so I can look up some information on the code for you? I may be able to reply sooner if I can get access to my database.

Hi Uri, I have a couple of questions. Previously I believe you said that you bypassed the compressor clutch and the a/c blew cold but I do not see a compressor clutch on your model. Your a/c compressor should run continuously and is controlled by a duty cycle solenoid.

Also, have you ever had any a/c pressure gauges connected to the system?

Hi , We did the bypass ( we have connected 12 v directly to the compressor ) And it worked . 2. We have emped the sistem and refills it with gas ( fully) And it worked good when it was connected directly.3. The code came form the Mercedes computer. The item no of the compressor in my car is XXXXXXXXXX (zero zero zero two three zero nine one one one ) Do you think it is the solenoid ( where is it located in the car)Thank you Uri

Ok, click here for the compressor I found when I ran the number on eBay. If you notice there is no compressor clutch on that compressor. The compressor turns all of the time and is controlled by the duty cycle solenoid towards the back of the compressor. Is that the one that you have?

Hi, at this point I think you need to get the fault codes erased and rechecked and also get the air conditioning system pressures tested. I don't trust the fault code they came up with since you had previously disconnected the compressor.

Ok - is there any way I can do that by mysalf? - to erace the codes ? The air perssure was tested when i put the new gas in the sistem, and when i did the buypass it was even befor i chang the gas and if worked great ,do you think I can do a bypass and "fix" it and Finished with it ?( like to make a switch next to the driver ?)I remained you that it didn't worked from the start ( befor I disconnected the compressor )

You cannot erase fault codes without using a factory level scan tool. You could bypass the compressor as you did before but by doing that your compressor will be on maximum cooling at all times. It could create a problem by doing it that way.

Ok , There for I have to go to the main Mercedes workhouse I will do that and update you But according to all the info what do you think the problem is ? Can you tell me what do you think it is?Thank you Uri

Hi Uri, at this point I suspect that you may have a faulty left front signal acquisition module. The module receives the a/c request from the a/c control panel and sends it to the compressor. With the Mercedes tester you can view the request from the a/c control and also view the compressor status to help diagnose this problem.

I will tell you that...the things you have to go through to be an Expert are quite rigorous.

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